Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Hi Its quite a long time now that I am searching articles on the conversion of the E 70 (Bavarian Kroco) to digital, without great success.  There are a few of them analog, DELTA, or early Digital that need conversion. The Loco is a TRIX design original and the firsts produced by Märklin are the 3448 and 3748 (Dig) from 1992. Its a very nice loco and till today there are many variations from Märklin. The other think is that is quiet easy to find the old analog or DELTA ones in good prices. My target is to achieve the following: 1. mSD/3 decoder without sound 2. LED lights WW both ends 3. LED Red twilight's 4. LED Cabin lights As we see there are some difficulties mainly from the limited space inside. See you back with the conversion process. Costas
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 3 users liked this useful post by ktsolias
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Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Hi First Step the disassembly of the loco The opening is quiet easy. Just unscrew the 2 screws from the under side and remove the body. Be careful not do any damage to the sensitive plastic hand grasps. And that is what is inside.  There is a big PCB on and the smaller reversing unit  Desolder everything and taking everything apart as well:  All the parts (except the body). Be careful with 4 stairs on the main module are very fragile!!!  The PCB is used for the change between hot shoe and photograph, to keep the capasitor of the motor, have the two contacts of the motor underneath, and the lines for the front lights.  The red plastic axle is for the changing between photograph and hot shoe from under the loco without the need to remove the body.  The motor is a DC three pole motor from Βühler the same with the one in the 3125 etc Red arrows.  Then I gone further with the opening and disassembly of the driving truck, so its possible to remove all the old hard grease, and clean very well everything.  The inspection did show any wear or damage. (the loco any way was working perfect in analog mode)  I did the same with the front truck witch is easier as the are no any gears. So after the opening the cleaning of everything I reassemble the trucks as there is no need to lost something, with very careful use of high quality silicone grease. Special care when change the traction tires as the bolts are very small and the all system of the wheels very sensitive. It's extremely difficult to find a spare part in case of any damage Then I start the measurements and the thinking what to do.... I will come back after the weekend.. Regards Costas Edited by user 12 November 2018 11:06:34(UTC)
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 6 users liked this useful post by ktsolias
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Joined: 22/01/2009(UTC) Posts: 14,879 Location: On 1965 Märklin Boulevard just around from Roco Square
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good luck, I wish the railing would have been of metal and not plastic.
John |
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Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Originally Posted by: river6109  good luck, I wish the railing would have been of metal and not plastic.
John Sorry the hand grabs are metal, painted black the railings are plastic.... But there are on LokMuseum new ones for 3,80 € Costas
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Joined: 25/09/2006(UTC) Posts: 945 Location: Sydney, NSW
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Hi Costas/All, I have done a conversion to the 3748 which has Telex couplers and LED lighting with warm white LEDs at the front and red LEDs for the rear lights. I didn't add cabin lights as there is little interior details. For those interested you can look at my article below. 3748 Telex and LED conversionLink corrected 01-01-2025 I hope someone finds it useful. Edited by user 01 January 2025 04:56:37(UTC)
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Ross
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 3 users liked this useful post by Ross
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Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Hi Next it is the time to decide about the decoder. There are two options according to my specifications: 1. 60972 2. 60982 Both are identical but differ in the packaging. The 60972 is a 21pin and the 60982 is plastic warped with 14 cables !!!!  The 60972 is to big (and thick) for the limited space above the PCB  So the decision is to use the smaller one the 60982. This packaging has some disadvantages: can not be removed easily to put another decoder and if you want program with the 60971 must use cables, witch is a bit complicated.  The dropping resistors for the LEDs will be soldered in a small vero board witch will seat where the reversing unit was.  I use classical 1kΩ resistors as there is enough space and are easier to handle than the SMD ones  So I will use the NEM color coding. The decoder programmed with the 60971 device, for the motor parameters, functions, and from there I dim the LEDs to the desirable output as well, and the programming of the red LEDs, as well the cabin LEDs Regards Costas
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 3 users liked this useful post by ktsolias
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Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Hi Next and most difficult the front and rear LED lights In the original there is a small bulb in a special cavity in the frame and two light pipes. The one from the bottom is for the two lower lights and the one at the top is for the main top light. But is only white!!! The difficulties arrived with the adding of Red taillights... The space is very limited and the frame is metal, so everything must be small and well insulated.  So after some measurements I decide to use 1,8mm through the hole type LEDs two WW and one RED each side which I solder with the BLUE wire (U+) and with the two function wires (F0 white or yellow, AUX 1 Green and AUX 2 Violet according to the direction and the polarity of course).  The complex fits fine in the small space  The final set with insulation with shrink tubes and the piece of black card between the lower two LED's (taillights) and the upper WW LED to prevent bleeding of the RED light to the top  The motor in place and the rear LED complex in place as well  Use of insulation tape to prevent any light bleeding  Test of the LEDs with the use of 1kΩ limited resistors: OK So the most difficult part finished. Of course there are and other solutions with SMD LED's or bi-color LEDs that may have the same or ever better results. In the next conversion of a E 70 I will try another solution, but the whole process is difficult and time consuming. Regards Costas
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 3 users liked this useful post by ktsolias
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Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Next I prepared the two cabin lights. On two small vero boards just SMD WW LED 1206 size. The resistors are in the other vero board.  Glued in place with hot glue  So everything is ready for final assembly Costas
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 4 users liked this useful post by ktsolias
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Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Hi Its time for the soldering of the various cables and the final assembly. The soldering was done according to the follow plan of the electronics:  The start  The completed modules except the front and rear lights  Everything completed and is in place  The final view before the checking The decoder programmed with the 60971 programmer and the mDT software. Its working great and is very fast. The motor parameters change from the default 5 soft DC motor to some more appropriate for the 3 pole DC motor (may change again latter after experiments). As far the space in the loco is very limited there was no place to do a transistor switch to control the red taillights on-off. So I used two functions to control the red LEDS one for each side. (I don't needed the 4th anyway) The direction of the red LEDs was programmed as follows: forward for the rear and backward for the front. The cabin lights dimmed to taste with the programmer as well (100 value). So the functions are f0/ = Front-Rear WW LEDs f1 = Rear Red LED f2 = Front Red LED f5 = Front cabin LED f6 = Rear cabin LED The loco tested and was working great. Excellent running, very smooth and quiet, nothing to do with the analog!!! Slow speed excellent. Lights working fine !!! Some images will follow Regards Costas
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 4 users liked this useful post by ktsolias
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Joined: 01/05/2016(UTC) Posts: 623 Location: Athens
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Hi And finally some pictures of the result: White lights  Red taillights, No bleeding at all to the upper light  Cabin Lights  Thank very much all of you for your nice comments. I hope that this conversion which is very special and not very easy will help other Märklin enthusiasts Best Regards Costas
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 4 users liked this useful post by ktsolias
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Joined: 18/02/2008(UTC) Posts: 1,334
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It looks very good. This is a great thread. Congratulations and thanks.
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Best regards, Miguel
Mostly Märklin H0.
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 1 user liked this useful post by mbarreto
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